The present invention relates to a method to attach biological molecules, such as oligonucleotides, peptides and proteins onto the surface of a glass or plastic support. The immobilization of biological molecules onto different substrates plays a crucial role in the development of the DNA microarray technology (Nature Genetics Supplement Vol 21, 1999). In recent years, the DNA microarray technology is gaining increasing acceptance in different areas of biomedical analysis. The technique, thanks to its versatility and miniaturization, has determined a considerable advancement in the sensitivity and throughput of different analysis. The coating methods used in the production of microarray slides represent a key factor for the success of the technique. Over the last few years, polymeric coatings have been developed based on polyacrylamide or polydimetylacrylamide gels for regioselective immobilization by the 3′ or 5′ end of oligonucleotides. A procedure for immobilizing DNA in polyacrylamide and dimethylacrylamide gels was developed by the Mirzabekov group at the Engelhardt Institute of Moscow (U.S. Pat. No. 0,981,734). The method consists of introducing functional groups onto a suitable polymeric support.
U.S. Pat. No. 5,861,247 discloses a method for constructing oligonucleotide matrices, which comprises confining a light sensitive fluid to a surface, exposing said light-sensitive fluid to a light pattern so as to cause the fluid exposed to the light to coalesce into discrete units and adhere to the surface and contacting each of the units with a set of different oligonucleotide molecules so as to allow the molecules to disperse into the units. The procedure to fix a regular set of polyacrylamide gel pads on a glass slide is cumbersome as it involves silanization of the glass and photopolymerization of acrylamide.
In another approach, Boles and coworkers at the Mosaic Technologies Inc. (U.S. Pat. No. 5,932,711 and U.S. Pat. No. 6,180,770) have developed chemistry for solid phase attachment of oligonucleotides based on the synthesis of oligonucleotides bearing 5′-terminal acrylamide modifications. Oligonucleotides bearing polymerizable functions are copolymerized with acrylamide/bisacrylamide and covalently attached to an organosilane surface to which acryloyl groups have previously been grafted. Also this procedure is time consuming and requires a careful control of operative parameters.
U.S. Pat. No. 6,121,027 discloses a process for the production of poly-, difunctional reagents having a polymeric backbone, one or more pendent photoreactive moieties, and two or more pendent bioactive groups. The reagent can be activated to form a bulk material or can be brought into contact with the surface of a previously formed biomaterial and activated to form a coating. The pendent bioactive groups function by promoting the attachment of specific nucleic acids and other molecules that are capable of binding noncovalently to specific and complementary portions of molecules.
U.S. Pat. No. 5,858,653 discloses a method to produce a polymeric support for oligonucleotide and DNA attachment. In this patent, a variety of homopolymers and copolymers resulting from addition or condensation polymerization provide a polymeric backbone capable of bearing ionic groups, photogroups and thermodynamically reactive groups. The method is based on the activation of latent photoreactive groups to generate active species which undergo addition to other active species on the same or on another molecule in such a way that a tridimensional network is generated in which reactive functions are properly spaced from the surface. Although very flexible, also this method involves the synthesis of complex copolymers whose composition may be difficult to be controlled.